In an organic EL element, a functional layer including at least an organic emissive layer is held between a pair of electrodes (see, for example, Patent Document 1). An organic EL panel including the organic EL element on a substrate has been developed for applications such as in luminescent displays and illuminations. The organic EL element emits light through recombination of holes and electrons in the organic emissive layer upon the injection of the holes from the positive electrode and the electrons from the negative electrode. The organic EL element has a so-called diode characteristic, in which current is unlikely to flow from the negative electrode side to the positive electrode side.
The organic EL element is problematic in the following respect. When a thin defect site occurs in a part of the functional layer as a result of, for example, inclusion of foreign material inside the functional layer in the production process, a current (leak current) flows in the opposite direction from the negative electrode to the positive electrode in response to the voltage applied to the organic EL element during the emission drive. This lowers the display quality of the organic EL element, resulting in, for example, uneven luminance.
In this connection, a method is known in which an energization treatment is performed that applies a voltage between the electrodes after forming the organic EL element in an organic EL element producing step to remove the negative electrode at the defect site causing the leak current, as disclosed in, for example, Patent Document 2. This method enables the defect site of the organic EL element to be removed in advance, and can thus suppress uneven luminance or the like, and stabilize the luminance characteristics of the organic EL element. It is also known that the defect site can be removed more quickly when the energization treatment is performed while heating the organic EL element at room temperature or higher temperatures.